Apparatus for the production of metal



June 3, 1958 w r G. ERVIN, JR, ET AL 2,837,478

' J APPARATUS FOR THE PRODUCTION 01-" METAL Filed Dec. 1-7. 1954 s Sheets-Sheet '1 E /70 1 go 3 I1 r 4 INVENTORS- GUY EflV/A/ JR. fag j Havana? 16! Uqrz June 3, 1958 e. ERVIN, JR. ET AL APPARATUS FOR THE PRODUCTION '01-" METAL Fil ed Dec. 17,. 1954 3 Sheets-Sheet 2 M 4 n 7 A TTOEZZ 1 3, 1958 a. ERVIN, JR, ETAL 2,837,473"

APPARATUS FOR THE PRODUCTION OF METAL Filed Dec. 17, 1954 3 Sheets-Sheet 3 Fig.5 N

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United States Patent 1 APPARATUS FQR THE PRODUCTION OF METAL Guy Ervin, .lr., Shrewsbury, and Herbert F. G. Ueltz,

Worcester, Mass, assignors to Norton Company, Worcester, Mass, a corporation of Massachusetts Application December 17, 1954, Serial No. 475,952

2 Claims. (Cl. 204-216) The invention relates to apparatus for the production of metal.

One object of the invention is to provide a continuously operating apparatus for the production of metal in the form of'sponge or otherwise not requiring to be shut down entirely for the replacement of an anode. Another object of the invention is to provide a continuously operating apparatus for the production of metal not requiring to be shut down on account of a coating of metal on the cathode. Another object of the invention is to provide a continuously operating apparatus for the production of metal not requiring to be shut down for the replacement of salt. Another object of the invention is to provide a continuously operating apparatus for the production of metal not requiring to be shut down for the complete removal of the metal produced.

Another object of the invention is greatly to reduce the cost of producing titanium ingots from which rods, sheets and bars can be rolled or drawn, parts forged and parts cast. Another object of the invention is to make it possible greatly to increase the production of useful titanium components for air frames and jet engines as titanium metal has properties which render it eminently suitable for use as such components if the demand for them could be satisfied at reasonable prices. Another object of the invention is to produce titanium at low cost for use in rockets and guided missiles and the like. Another object of the invention is to provide metal producing apparatus which is simple in construction and can be made in many sizes and which will produce metal continuously at least for a long period of time.

Another object is to provide a continuous apparatus for the electrolytic winning of metals of the subgroups of groups IV, V and VI of the periodic classification of the elements, by means of electrolysis of fused salt baths.

Another object of the invention is greatly to reduce the cost of producing zirconium ingots from which rods, sheets and bars can be rolled or drawn, parts forged and parts cast. Another object of the invention is to increase the production of zirconium articles for use in chemical equipment since zirconium metal has excellent resistance to many types of corrosive chemical attack.

Other objects will be in part obvious or in part pointed out hereinafter.

In the accompanying drawings illustrating one of many possible embodiments of the apparatus of this invention,

Figure 1 is a vertical sectional view of the apparatus,

Figure 2 is a fragmentary view on an enlarged scale illustrating one edge of an anode plate showing the bayonet socket therein,

Figure 3 is a view on the same scale as Figure l of a bayonet rod for the easy replacement of the anode plates,

Figure 4 is a vertical sectional view taken on the line 44 of Figure 1,

Figure 5 is a plan view of the lower part of the apparatus, the cap having been removed,

2,837,478 Patented June 3, 1958 ice Figure 6 is a sectional view on an enlarged scale taken along the line 6-6 of Figure 1,

Figure 7 is a fragmentary view on an enlarged scale illustrating a commutator, showing a cathode shaft in section along the line 77 of Figure 4.

Referring first to Figure 1, the supporting part of the apparatus may conveniently take the form of an open. top steel box 10 having flanges 11 to which is detachably bolted by means of bolts 12 through corresponding flanges 13, a cap frame 14 also conveniently made of steel with which the flanges 13 are integral. Between the flanges 11' and 13 we provide gasket material 15 which may be made of asbestos composition. In this illustrative embodiment the box 10 is a rectangular parallelepiped .and the cap frame 14 isa triangular prism with one dihedral angle of degrees at the top, this prism merging into arectangular parallelepipedal bottom portion which has the flanges 13.

The box 10, excepting where instrument'alities extend\ through it, is filled with refractory insulating bricks 20, no attempt being made in the drawings to illustrate individual bricks since the lining of the box 10 is a masonry job. These bricks 243 can be made of porous fire clay which is reasonably inexpensive. They are both thermally insulating and electrically insulating. While theoretically the separate-insulation of the electrical leads renders further insulation unnecessary, it is highly desirable to avoid short-circuits due to insulation failure and to avoid stray currents. The cap frame 14 is also partially filled with the same kind of refractory insulating bricks 25 and here again we have not attempted to illustrate the bricks individually.

Supported by the bricks 20 is a hearth 30 made of graphite and illustratively this can be made in a single piece. As shown it has the shape of two non-rectangular parallelepipeds joined together to form a dihedral angle on top with the apex constituting the low point of the hearth and with integral sides 30:: spanning the dihedral. The space bounded by the dihedral angle and the sides is a well. We further provide a graphite cap 31 underneath and supporting the bricks 25 which is also desirably an integral piece. This is shown as having a dihedral angle with the apex at the high point and thus the hearth 30 and cap 31 enclose a generous space as the dihedral angle of the cap 31 is illustratively 90 degrees although the dihedral angle of the hearth 30 is shown as obtuse, but other angles could be adopted for either or both. This cap 31 is supported by long bolts 33 extendingthrough the cap 31 and through the side walls of thecap frame14.

Referring now to Figures 4 and 5, secured to the outside of the box. if] and of the cap frame 14 by means of bolts 35 extending through insulating bushings 36 are ball bearing cases 37 supporting ball bearings 38 which support hollow shafts 40 which can be made of steel. The shafts 49 are press fitted into bores inthe ends of trunnion portions 45 of a cathode roller 50. This cathode roller should be shaped as a body of revolution of which the most convenient form is a cylinder and it should be made of some metal which will not contaminate the metal being extracted. In the case of the extraction of titanium it is best to provide a titanium cathode roller 50. This cathode. roller is maintained electronegative and revolves in a molten salt bath 55 in which are anode plates 60 made of carbide of the metal being extracted, for example in the above instance of titanium carbide, the anode plates 60 being supported by the graphite hearth 30. The anode plates 60 are maintained electropositive. As the roller 50 rotates the desired metal is deposited thereon in'the salt bath 55 in the form of sponge metal and, rising from the salt bath by reason of the rotation of the roller50, it is eventually brought to a doctor blade 65 located on the down moving side of the roller which doctor blade scrapes off the sponge metal which is eventually deposited in a well lined with inert refractory material such as sintered aluminum oxide plates 71, 72 and 73, which well 70 is continued by a lower well 75 in the shape of a hollow steel rectangular parallelepipedal box 76 merging into a removable box 78 also made of steel and bolted totthe box 76 by means of bolts 80 extending into flanges 81 and 82 of the boxes 76 and 78, with suitable gasket material 83 between the flanges. We will now resume the description of the mounting for and the means for rotating the roller 50 as well as the device to make it electronegative.

Secured to one hollow shaft 40 well clear of the box 10 and outside of a .cover plate 85 on a protected casing 86 is a sprocket gear 87. This is connected by a sprocket chain 88 to a sprocket gear 89 secured to the output shaft 90 of a reduction gear mechanism 91 the input shaft 92 of which is coupled by a coupling 93 to the armature shaft 94 of a motor 95 which preferably is a direct current motor operated through a circuit including a rheostat, not shown, whereby it can be run very slowly. We have operated our apparatus with the cathode roller 50 rotating at the slow speed of four revolutions per hour.

It will be seen from Figure 4 that there are two casings 86 each having a cover plate 85, one on each side of the apparatus as therein viewed. Each plate 85 has a central hub through which the shafts 40 extend. Screwed onto the hubs 105 are caps 106 retaining gasket material 107 and thus the hubs 105, caps 106 and gasket material 107 constitute stufiing boxes sealing the shafts 40 but allowing rotation thereof.

While within the scope of our invention in certain aspects any salt can be used which is operative in the process, for many metals we believe that the salt should be a halide of an alkali metal or a halide of an alkaline earth metal. Metals which we contemplate extracting by means of the apparatus hereof are those in the following table giving the group numbers according to one classification on top and the atomic numbers underneath each metal.

Table IV B V B VI 13 Titanium Vanadium Chromium 22 23 24 Zirconium Niobium Molybdenum 40 41 42 Hafnium Tantalum Wolfram 72 73 (Tun7gsten) The general process of extracting these metals from their carbides is dealt with in our copending applications, Serial Nos. 394,753, 313,171, 356,426, 356,423, 356,425, 356,428, 356,424, and 356,427. However, the present invention can be used for the extraction of other elements from compounds. Y

The alkali metals contemplated are those usually considered to be such, namely sodium, potassium, lithium, rubidium and cesium. Naturally because of expense sodium and potassium will be preferred. The alkaline earth metals contemplated are those usually considered to be such including magnesium about which there is some dispute nowadays, to wit, calcium, magnesium, barium and strontium.

Sodium chloride, the commonest of all the halides of these metals has a melting point of 800 C The melting points of the other 35 can be found in handbooks and other literature. We now prefer a eutectic mixture of 40 mols of potassium chloride and 60 mols of lithium chloride having a melting point of about 350 C. as there are always some advantages in avoiding high temperatures in theuse of any apparatus. The top temperature limitation is the melting point of the metal being electrodeposited which in the case of titanium is 1660 C. For many salt baths which have a relatively high vapor pressure, a maximum operating temperature may be around 1100 C. When the heating of the bath is external, but may go to higher temperatures when internal electrical heat is supplied in significant amounts. Consequently it is desirable to provide means for cooling the shafts 40.

Referring now to Figure 4, pipes 110 extend into the hollow shafts 40 with a clearance between them and the inward ends of the pipes 110 are unplugged. Screwed into the outer internally threaded ends are short pipes 112 of the shafts 40 through which the pipes 110 extend also with a clearance. Journalled on the pipes 110 by means of ball bearings 115 are L-pipe connections 117, the ball bearings 115 being held in place by means of caps screwed onto the L-pipe'connections 117. Axially located pipes are screwed into the outer ends of the L-pipe connections 117 to make connection hydraulically to the pipes 110. Radially located pipes 127 are screwed into the L-pipe connections 117 to make coolant connection to the spaces between the shafts 40 and the pipes 110. Coolant seals 128 are provided between the outsides of the short pipes 12 and the insides of the L-pipe connections 117 to keep coolant fluid away from the ball bearings 115 and also from leaking out of the circuit.

The preferred cooling fluid is water and preferably the pipes 125 are inlet pipes and the pipes 127are outlet pipes. Without further description it will be seen that the rotating shafts 40 are water cooled from water circulated between pipes 125 and 127. This is desirable to keep the bearings 33 and the shafts 40 from deteriorating.

Referring now to Figures 1 and 4, we may provide electric heating bars 130 extending through the hearth 30 and electric heating bars 131 extending through the cap 31. These bars 130 and 131 which extend through and are supported by refractory insulating bushings 132 and 133 located in bores in the bricks 20 and 25 respectively and extending through holes in box 10 and cap frame 14 respectively can be made of recrystallized silicon carbide with siliconized cold ends 135 in a manner now well known. As suchheating bars can now be procured on the open market from several sources we need not further describe them. The bars 130 and 131 can be energized in any desired manner and are preferably connected in parallel. Without showing every last connection which would be obvious to any electrician we illustrate them as connected to power through customary spring clips 137 holding braided metal wire tape 138 against the cold ends 135, the tape 138 being connected to binding posts 140 extending through the casings 86 to which insulated cables connected to a source of power are secured.

Referring now to Figure 4, in order to keep the roller 50 electronegative, we provide a commutator ring to which are connected cables 151 leading to the negative side of a source of direct current electricity. The commutator ring 150 is mounted on a commutator bushing 152 which is secured as by means of a set screw 153 to one of the shafts 40 which is, of course, a metal shaft preferably steel and so is a good conductor of electricity and is in direct engagement with one of the trunnions 45 constituting an integral part of the roller cathode 50. For insulating the shafts 40 we provide insulating plates betweenthe box 10 and the cap frame 14 on one side and the ball bearing cases 37 on the other side and the insulating bushings 36 previously mentioned. For the same purpose we provide an insulating sleeve, not shown, between the sprocket gear 87 and its shawt 40 and the pipes 125 and 127 are connected to water supply and discharge by water hoses, not shown. The gasket material 107 is also insulating.

Referring to Figure 7, the commutator ring is shown as made in two parts secured together at one side by a clamp 154 on the end of an arm 155 to which are secured the cables 151 and which is connected to cables 156 connected to the negative side of the'source. The parts "of the ring 150 are connected on the other side by a spring 157 extending between pins 158 which are driven into the parts of the ring. Thus the commutator ring 150 is held in pressure engagement against the commutator bushing 152 and it is connected to power through generous cables 151 thus making the resistance at this part of the circuit negligible while the spring pressure greatly reduces the ohmic resistance in the jump between the stationary commutator and the rotating commutator. Naturally, in any manner not shown, the arm 155 is held reasonably rigid.

Referring now to Figures 1 and 4, for keeping the anode plates 60 electropositive, we provide an electric cable 160 leading to the positive source of direct current electricity which is connected to a clamp 161 secured to a shaft 165 extending through a vertical bore in the bricks 20 and screwed into the graphite hearth 30 upon which the anode plates 60 rest. This might be all but we prefer to water-cool the shaft 165 and so it is made hollow, and we also prefer to seal the orifice through the bottom of the box and therefore further construction shortly to be described is preferably provided.

Extending upwardly into the hollow shaft 165 is a pipe 168 the upper end of which is unplugged. This pipe 168 extends at its lower end into a pipe 170 with which it makes a water-tight engagement, and the bottom of the pipe 170 is connected to a rubber hose 171 through which water is circulated and for example this can be the inlet side of the water connection. Thus the cold Water goes far into the hollow shaft 165 and returns outside of the pipe 168 there being a clearance between them. Screwed into the bottom of the hollow shaft 165 is a short pipe 175, there being a clearance between the pipe 168 and the pipe 175. Connected to the bottom of the short pipe 175 is a plumbing T-connection 177 the bottom of which is in screw threaded engagement with the pipe 170. The third connection of the T 177 is connected to a pipe 179 on the end of which is a rubber hose 180 leading, for example, to drain. The rubber hoses 171 and 1811 provide electrical insulation for this part of the circuit.

Still referring to Figure 1, a heavy pipe 185 is welded to the bottom of the box 10 around the hole 184 through which the shaft 165 extends, with a generous clearance between them as shown. At the bottom of this pipe 185 is secured in screw threaded engagement a coupling 186 which has an internal flange 187 on the bottom and secures in place an insulating sealing bushing 188 while another insulating bushing 189 is located between the pipe 185 and sealing rings 191) and 191 located as shown complete the sealing of this assembly against egress of any leaking vapors or molten salt and complete the insulation.

Referring now to Figures 1 and 5, the doctor blade 65 is secured by screws 195 to a shaft 196 which extend through insulating bushings 197 retained in place by semicircular cut-outs in each of the box 10 and the cap frame 14. At one end of the shaft 196 is an arm 200 secured thereto by a set screw 201 through a hub 202 at the end of the arm 200 which is shown as a rod and an adjustable weight 203 in the form of a sleeve secured to the armrod 200 by a set screw 204 provides a component of a couple to hold the doctor blade 65 with a limited amount of pressure against the roller cathode 50. The sponge metal clings to the roller 50 with slight adhesion as it is deposited thereon but is easily scraped off by the doctor blade 65.

We have found that under many conditions of operation the sponge metal collecting on the doctor blade 65 clings to it somewhat also, at least doesnt fall off quickly enough for the best results, or may not in certain cases. Optionally, therefore, we provide a scraper to scrape the sponge from the docto blade and to cause it to fall into the well 70 and thence into the well 75. This may take the form of a wide bar 210 (Figure 1) at the end of a 6 I v 8 long rod 211 extending through a friction gasket 212 inside of a cap 213v screwed into the end of a pipe 214 welded to the outside of the cap frame 14, there being a hole in the frame inside the area of the pipe 214, and the rod 211 extending through a bore in the bricks 25 and a lined bore in the cap 31. The rod 211 has any desired type of handle 218 which may be a piece of insulation by which it can be pushed downwardly to scrape off the doctor blade 65 at any time desired, and then raised again out of the way where it stays by mere friction. The cathode roller 50 itself will act as an aligning mechanism for the scraper 210 as it is pushed down wardly. It is highly desirable in the case of some metals at least, particularly in the case of titanium, to provide an inert atmosphere around the cathode roller 50, that is to say in the chamber provided by the space between the hearth 30 and the cap 3 1, and also in the wells 70 and 75. The inert gases are argon, helium, neon, krypton and xenon. Helium and argon being 'the least expensive are preferred but of these argon is preferred because of its high specific gravity which is greater than that of air, helium being the lightest of all substances except hydrogen. There is a definite relationship between the specific gravity of a gas and its diffusion properties and in general the heavier gases diffuse less readily. In order to avoid wastage of the inert gas one which has a poor diffusion rate is preferred.

For providing the inert. atmosphere we have a pipe 220 welded to the outside of the box 76 through the ends of a hole inside the area of the pipe 220. The pipe 220 is connected by a rubber hose 221 to the argon circuit and illustratively this may be the inlet hose. For the same purpose we provide an alumina tube 225 (which is quite impervious to gases whereas the bricks 25 are not) extending through the bricks 25 and cemented against the inside of the cap frame 14 and in tight communication with a bore 227 through the cap 31. This.

tube 225 is in connection with a pipe 230 welded to the outside of the cap frame 14, with a hole through the frame inside the area of the pipe 231). The upper end of the pipe 230 is screw threaded and is engaged by a cap 232 which holds in place a sealing ring 233 and the cap 232 has a glass window 235 for pyrometric sighting of the molten salt to determine the temperature thereof. A pipe 240 welded to the outside of the pipe 230, there being a hole through the latter within the area of the former, provides the other argon or other inert gas connection, illustratively the exhaust connection, and a rubber hose 241 leads to apparatus for the recovery of the argon or to a suitable exhaust. While argon itself is not poisonous there will be some entrained vapors of salt which are at least corrosive.

Referring now to Figures 1 and 6, we provide gas lock boxes 250 for the replacement of the anodes without opening the chamber formed by the space between the hearth 30 and the cap 33. Impervious alumina plates 251 rest on the bricks 20 with their upper faces flush with and in the same plane as the sides of the dihedral angle of the hearth 30. At the right hand side in Figure 1 the plate 251 is in contact with the hearth 30 and extends between it and the frame 14. At the left hand side plate 251 is in contact with the plate 71 and is flush with it and extends to the frame 14.

By comparison of Figures 1 and 6, it will be seen that the gas lock boxes 250 are hollow rectangular parallelepipeds which are welded to the outside of the cap frame 14 with a passage through the latter rectangular in shape and within the area of the ends of the boxes 250, and there is clearance through the bricks 25 so that the under side of the bricks 25 and the plates 251 form slanting guideways or passages which are continuations of the passages formed between the top and bottom plates of boxes 250. The boxes 250 have slides 255 made of refractory wear resistant material, for example of molded aluminum oxide the same as many other parts of the apparatus which geometrically have the shape of prisms the upper apexes of which are in line with the upper surfaces of the plates 251. S lidcways 258 and 259 are welded to the tops of the boxes 250 and receive gates 260 and 261 which are simply metal plates, the gates 26!) having doors 262 in the shape of recesses.

Referring to Figure 3, a bayonet 270 is simply a long steel rod having an insulating handle 271 and a T-shaped bayonet lock 272 at the other end. It can be inserted through either of the doors 262 andthen pushed further downwardly by opening the gate 261. The bayonet 270 practically fills the door 262 through which it is inserted so when the gate 261 is opened there is still no 'major opening for egress of gases (but a minor opening in both doors due to imperfect fit especially below the horizontal diameter of the rod 270 for flushing the gas lock with inert gas from the chamber). As shown in Figure 2 the anode plates 60 have inwardly recessed holes 275 with slots 276 through which the projections of the bayonet lock 272 can be inserted with the bayonet270 in the proper angular position. To find the position is merely a matter of feeling or there can be marks 277 onth e handle 271. When the bayonet lock 272 is inserted into bayonet slots 276 and then turned it will notcome'out of the hole 275 unless turned again to the rightposition for it to emerge through the slots 276. Thus ananode plate 60 can be withdrawn into the gas lockforrned by the box 259, and then the gate 261 can be closed and the anode plate 60 can be removed from the locli'without loss of gas. Without further description it will readily be seen that a fresh anode plate can readily be'iplaced on the hearth 30 without loss of gas or with little loss thereof. The gates 261 have slots for the reception of the slides 255 so that when the gates 261 are closed they efiectively seal the gas locks.

Thus the gas lock boxes 250 provide means for replacing anode plate 60 without shutting down' the apparatus. .The removable box 78 provides means for removing the sponge metal collected without shutting down the apparatus. A plate can be held against the bottomof the opening of the well 75 while the box 78 is being emptied to prevent entrance of air. The pipe 230 withitsc'ap 232, the tube 225 and the bore 227 provide means for replenishing the salt bath 55 without shutting down the apparatus. The salt can be briquetted into cylindrical bodies of diameter slightly less than the inside diameter of the pipe 230 tube 225 and bore 227 so that littleg'as will be lost and no air will be entrained during the replenishment of salt. The apparatus doesnt' have to be shut down to remove an accumulation of metal on the cathode as it is scraped oif as fast as it is formed. In many prior apparatuses for the extraction of metal electrolytically an overgrowth of metal on the "cathode changed the ohmic resistance of the cell and eventually the process had to be stopped for the removal of the deposited metal. Not only did'accumulation change the ohmic resistance of the cell but it also affected the purity of the metal being recovered by making the path through the electrolyte too short.

The box 10 can, of course, be supported in any desired manner but conveniently it can be secured to legs 280 which illustratively are made out of angle iron steel and welded to the corners of the box 10.

Apparatus other than the doctor blade 65 which is a form of scraper can be used to remove the sponge metal from the cathode 50 in accordance with our invention in certain aspects. For example a revolving brush might be used with or without a separate scraper to cooperate therewith. The metal itself may collect on the revolving cathode roller 50 in the form of sponge as it is understood in metallurgy or in some cases it may be granular or powdery in appearance. So long as it can be removed during the process or action of the apparatus it makes little diiference What it is called. '7

It will thus be seen that there has been provided by this invention apparatus for the production of sponge metal'in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiments above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted illustrative and not in a limiting sense. v i

We claim: l

1. Electrolytic apparatus for the production of refractory metal from its carbide comprising a chamber having a well for molten salt said chamber being refractory, means to circulate inert gas into and through said chamber, a metal cathode which is a body of revolution in said well where it can contact the molten salt in the well, means journalling said cathode for rotation, driving means outside of said apparatus and connected to said cathode through said refractory chamber to rotate said cathode, a doctor blade to scrape deposited metal from said cathode, another well positioned to collect said scraped metal, a carbide anode in said first well Where it can contact the molten salt in the well, a rod connectable to and disconnectable from said anode, a guideway to guide said anode into and out of said well, a gas lock connected to said chamber and in line with the guideway, an inside movable gate' for said gaslock at the end of said guideway movable to close said gas lock from said well and to open it to said well, and an outside movable gate for said gas lock movable to close said gas lock from the atmosphere outside of the apparatus and to open it to said atmosphere, whereby said anode can be withdrawn from said well into said gas lock and then to the outside of the apparatus to be replaced and then the replacement anode can be introduced through said lock into said well, and means for flushing said gas lock of air by inert gas after the outside gate has been opened and a replacement anode has been inserted therein.

' 2. Electrolytic apparatus for the production of refractory metal from its carbide in accordance with claiml having a scraper in line with the doctor blade to scrape metal from said doctor blade and means extending through the chamber to operate the scraper from outside the apparatus.

References Cited in the file of this patent UNITED STATES PATENTS 531,309 Guillaume .4 Dec. 25, 1894 533,596 House Feb. 5, 1895 1,365,140 Adam Jan. 11, 1921 1,538,390 Ewan May 19, 1925 FOREIGN PATENTS 137,626 Sweden Oct. 14, 1952 

1. ELECTROLYTIC APPARATUS FOR THE PRODUCTION OF REFRACTORY METAL FROM ITS CARBIDE COMPRISING A CHAMBER HAVING A WELL FOR MOLTEN SALD SAID CHAMBER BEING REFRACTORY, MEANS TO CIRCULATE INERT GAS INTO AND THROUGH SAID CHAMBER, A METAL CATHODE WHICH IS A BODY OF REVOLUTION IN SAID WELL WHERE IT CAN CONTACT THE MOLTEN SALT IN THE WELL, MEANS JOURNALLING SAID CATHODE FOR ROTATION, DRIVING MEANS OUTSIDE OF SAID APPARATUS AND CONNECTED TO SAID CATHODE THROUGH SAID REFRACTORY CHAMBER TO ROTATE SAID CATHODE, A DOCTOR BLADE TO SCRAPE DEPOSITED METAL FROM SAID CATHODE, ANOTHER WELL POSITIONE TO COLLECT SAID SCRAPED METAL, A CARBIDE ANODE IN SAID FIRST WELL WHERE IT CAN CONTACT THE MOLTEN SALT IN THE WELL, A ROD CONNECTABLE TO AND DISCONNECTABLE FROM SAID ANODE, A GUIDEWAY TO GUIDE SAID ANODE INTO AND OUT OF SAID WELL, A GAS LOCK CONNECTED TO SAID CHAMBER AND IN LINE WITH THE GUIDEWAY, AN INSIDE MOVABLE GATE FOR SAID GAS LOCK AT THE END OF SAID GUIDEWAY 